Phys. Rev. C
66,
034614
(2002)
[14 pages]
Polarization measurements in neutral pion photoproduction
K. Wijesooriya et al.
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K. Wijesooriya1,*, A. Afanasev21,27, M. Amarian12, K. Aniol4, S. Becher10, K. Benslama24, L. Bimbot23, P. Bosted17, E. J. Brash24, J. Calarco19, Z. Chai18, C. C. Chang16, T. Chang11, J. P. Chen27, S. Choi26, E. Chudakov27, S. Churchwell7, D. Crovelli25, S. Dieterich25, S. Dumalski24, D. Dutta18, M. Epstein4, K. Fissum15, B. Fox5, S. Frullani12, H. Gao18, J. Gao3, F. Garibaldi12, O. Gayou2,29, R. Gilman25,27, A. Glamazdin14, C. Glashausser25, J. Gomez27, V. Gorbenko14, O. Hansen27, R. J. Holt1,11, J. Hovdebo24, G. M. Huber24, C. W. de Jager27, X. Jiang25, C. Jones3, M. K. Jones22, J. Kelly16, E. Kinney5, E. Kooijman13, G. Kumbartzki25, M. Kuss27, J. LeRose27, M. Liang27, R. Lindgren28, N. Liyanage27, S. Malov25, D. J. Margaziotis4, P. Markowitz8, K. McCormick6, D. Meekins9, Z. -E. Meziani26, R. Michaels27, J. Mitchell27, L. Morand25, C. F. Perdrisat29, R. Pomatsalyuk14, V. Punjabi20, R. D. Ransome25, R. Roche9, M. Rvachev18, A. Saha27, A. Sarty9,†, E. C. Schulte1,11, D. Simon10, S. Strauch25,‡, R. Suleiman13, L. Todor22, P. E. Ulmer22, G. M. Urciuoli12, B. Wojtsekhowski27, F. Xiong18, and W. Xu18
1Argonne National Laboratory, Argonne, Illinois 60439
2Université Blaise Pascal/IN2P3, F-63177 Aubière, France
3California Institute of Technology, Pasadena, California 91125
4California State University, Los Angeles, California 90032
5University of Colorado, CB 446, Boulder, Colorado 80309
6DAPNIA, Saclay, France
7Duke University, Durham, North Carolina 27706
8Florida International University, Miami, Florida 33199
9Florida State University, Tallahassee, Florida 32306
10University of Georgia, Athens, Georgia 30602
11University of Illinois, Urbana-Champaign, Illinois 61801
12INFN, Sezione Sanitá and Istituto Superiore di Sanitá, Laboratorio di Fisica, I-00161 Rome, Italy
13Kent State University, Kent, Ohio 44242
14Kharkov Institute of Physics and Technology, Kharkov 310108, Ukraine
15University of Lund, P.O. Box 118, S-221 00 Lund, Sweden
16University of Maryland, College Park, Maryland 20742
17University of Massachusetts, Amherst, Massachusetts 01003
18Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
19University of New Hampshire, Durham, New Hampshire 03824
20Norfolk State University, Norfolk, Virginia 23504
21North Carolina Central University, Durham, North Carolina 27707
22Old Dominion University, Norfolk, Virginia 23529
23Institut de Physique Nucléaire, F-91406 Orsay, France
24University of Regina, Regina, Saskatchewan, Canada S4S 0A2
25Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854
26Temple University, Philadelphia, Pennsylvania 19122
27Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606
28University of Virginia, Charlottesville, Virginia 22901
29College of William and Mary, Williamsburg, Virginia 23187
Received 9 May 2002; published 26 September 2002
We present measurements of the recoil proton polarization for the 1H(γ⃗,p⃗)π0 reaction for θc.m.π=60°–135° and for photon energies up to 4.1 GeV. These are the first data in this reaction for polarization transfer with circularly polarized photons. Various theoretical models are compared with the results. No evidence for hadron helicity conservation is observed. Models that employ factorization are not favored. It appears from the strong angular dependence of the induced polarization at photon energies of 2.5 and 3.1 GeV that a relatively high spin resonance or background amplitude might exist in this energy region.
© 2002 The American Physical Society
URL:
http://link.aps.org/doi/10.1103/PhysRevC.66.034614
DOI:
10.1103/PhysRevC.66.034614
PACS:
13.60.Le, 24.70.+s, 24.85.+p, 25.20.Lj
*Corresponding author. Email address: krishniw@jlab.org †Present address: St. Mary’s University, Halifax, Nova Scotia, Canada B3H 3C3. ‡Present address: George Washington University, Washington DC 20052.
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